Federal authorities Thursday shut down Fung Wah Bus Transportation Inc., the best known of the East Coast’s “Chinatown bus” companies, citing a pattern of safety violations that “substantially increase the likelihood of serious injury or death” for drivers and passengers.

Boston-based Fung Wah was ordered to suspend all operations Thursday by the Federal Motor Carrier Safety Administration, the same regulator that ordered the company to pull the bulk of its bus fleet off the road late last month after inspectors in Massachusetts flagged cracked chassis and other flaws.

Thursday’s order went further, deeming the company’s operation of buses “an imminent hazard” to motorists and ordering it to shut down altogether.

Investigators alleged that the company hasn’t properly maintained its buses and “permits its drivers to make fraudulent or intentionally false statements” on inspection reports to hide defects from investigators. The company also doesn’t ensure that its drivers are qualified to drive intercity buses, or conduct required drug and alcohol screenings, the closure order said.

No one answered phones at the company’s New York and Boston offices. A notice on the Fung Wah website said service had been suspended pending investigation of the company’s buses.

In order to resume operations, the FMCSA said, the company would have to submit to safety inspection, overhaul its scrutiny of drivers and equipment and “drastically change its maintenance posture, philosophy and infrastructure.”

Low-cost intercity bus carriers have flourished in recent years, especially between cities along the Eastern seaboard, including Boston, New York, and Washington. Federal authorities began a crackdown in spring 2012 on carriers with frequent safety violations, shuttering down 26 companies on a single day last May.

Fung Wah has racked up at least $78,000 in safety violations with the FMCSA since 2005, according to online records.